Abstract: A new and improved vehicle cab heater includes a shroud assembly capable of fitting over a radiator and radiator fan on a water-cooled engine. A conduit is connected between the vehicle cab and the shroud assembly for conveying heated air from the radiator to the vehicle cab. A manually operated valve assembly is located at an end of the conduit. The valve assembly includes an exterior portion located outside of the vehicle cab and includes an interior portion located inside the vehicle cab. The valve assembly includes an exterior valve subassembly for controlling air flow from the shroud assembly to outside the vehicle cab, and the valve assembly also includes an interior valve subassembly for controlling air flow from the shroud assembly to inside the vehicle cab. A handle assembly is capable of being attached to the valve assembly. The valve assembly includes a handle-receiving portion and a guide slot located in an extension assembly.